K

ksauce

Well Known Member
Patron
Hi all,

Yesterday I was flying from Vegas to San Diego and had to put down early in Borrego Springs due to a P-Mag problem. I'm hoping it's just a timing thing and a quick reset will be all that's required, but if anyone might be able to point me in the direction of someone with tools I'd be most grateful. I'm not in any rush as I'm in San Diego all week, so I'll gladly work on any schedule. As always, thanks VAF.
 
Pmag

Well first off does the engine run rough on one or both of the Pmags?....

I.e can you describe the symptoms?

If it as you say, either the Pmag has reverted to its original timing or perhaps you have had a magnet shift which the latest fix (return to the factory) will fix..

You might be beter off calling Brad at emagair tomorrow.

You only need a hlf inch open ended wrench, a 1/8th allen wrench and a small screwdriver to remove the whole thing...Should be easy to pick up locally.



Frank
 
Also determine how you did the timing and if you have had any mods performed that corrected failure modes. Apparently the blow method is not the best. I saw someone time it like a normal mag and it was simple.

With a mag problem, you need to be willing to change from both mags to Left and Right to determine if it runs ok on a single mag....and help isolate the offender.
 
Last edited:
I have 1 pmag and 1 mag. The pmag is a 114 series. I did switch off the pmag (I had to to get the CHTs down to reasonable levels) and the problem definitely went away. I'll paste the email I sent to emag below:

I recently installed a 114 series P-Mag in my RV-6A. I have maybe 20 hours on it and all was well until yesterday. I was on a cross country flight from Las Vegas to San Diego at 12,500 feet and noticed a surging of the prop. It would rev up, and then down repeatedly. I also noticed that the CHTs were very high (the hottest was well over 450 degrees). If I reduced RPM (I have a fixed pitch prop) the surging would generally go away; however, if I was operating near full throttle the problem would intermittently come back. The high CHTs remained unless I switched the P-Mag off and flew only on the mag. There was a
considerable drop in power when doing so on the order of 300 RPM or so but I expect that to be normal. I descended to 10,500 and the problems persisted.

For prudence, I landed short of San Diego. When I shut down, I pulled the mixture as normal but the engine kept stumbling. I wound up just switching off the mags to kill the engine. Upon further reflection on the ground, I do remember that when I initially started up the first time that day, the engine pulled through one blade, paused, and then started. I did have to increase the throttle a bit more than usual to get the engine idling smoothly. I pulled the cowl and checked the MAP connections and wiring and all seemed well. I didn't have a chance to check the LED with the engine at TDC as I was running out of daylight.
 
Tools, etc. available

Kevin, if you need tools, etc. Give me a call at 619-701-7180. I'm at Gillespie Field in El Cajon, just outside of San Diego. I'm at Trio Avionics, and you can have access to any resources we can muster.

Jerry
 
ksauce said:
When I shut down, I pulled the mixture as normal but the engine kept stumbling. I wound up just switching off the mags to kill the engine.
Click to expand...

I'm confused about this statement. Wouldn't removing the fuel from your engine definitely cause it to stop? Is it possible the surging problem was due to your mixture fluxuating, and a secondary indication of this would be the fact that your mixture didn't kill the engine?

Possibly removing the P-Mag (thereby removing the advance) could've seemed to fix the problem, when it was really the mixture. Of course, this is all just speculation in an attempt to get you to look for other possible sources. Good luck, and keep us all posted.
 
You must have internet access...

But just in case here is their phone number:

(817) 444 5310
 
H-m-m-m-m

Just curious. If the problem went away when the P_Mag was off, why make the enroute stop? I have had mags fail over the years and the procedure I follow is to use the good mag in the redundant system to reach my destination.

Bob Axsom
 
Bob Axsom said:
Just curious. If the problem went away when the P_Mag was off, why make the enroute stop? I have had mags fail over the years and the procedure I follow is to use the good mag in the redundant system to reach my destination.

Bob Axsom
Click to expand...

Don't understand why some people on this site question other peoples decisions when it comes to safety. Here's AWAG. Possibly a defunct mag has shed a part or two into the engine.
Tin Man
 
Update

For those interested, thanks to the OVERWHELMING generosity of the folks at Trio Avionics I was able to limp the plane home on Monday. Jerry flew me over in his LongEZ Monday and Sid flew with us in his LongEZ. They helped me check what I could (according to Emag) and button the plane back up. The PMag definitely wasn't healthy but I decided I could make the flight.

Jerry stayed on my wing for the short hop over the hills. I limited myself to 100 mph and I'm sure he had a hard time holding the reigns on his LongEZ that tight. I landed without event at KSEE and taxied to their place. They gave me tools and hangar space. I took out the P-Mag and we overnighted it to EMag.

In terms of the P-Mag itself, Emag received it on Tuesday and had it on their bench. They called on Wednesday to tell me that the P-Mag had lost all of it's factory defaults. It was still firing fine, but that all of the ignition curves had been changed. They had asked if I had played around with any of the settings and I hadn't. The stored internal temp reported being within range, but that isn't a guarantee as all of the other internal variables had somehow changed.

They've apparently only had one other failure of a 114 series so unfortunately this isn't a cut and dry case of cause and effect. They replaced the main circuit board and I had them overnight it back to me. I should have it this morning and will try to have it back up and running by this afternoon. More to follow...
 
Heh heh....didn't you get that P-mag off E-bay Kevin for a "steal";) If I remember right. Didn't need my hangar this time...Glad you got her back and fixed.
 
Kevin, help the education process here

Does the ignition curve change mean that the Pmag could/would have fired at a bad time and resulted in the symptoms that you saw? I am guessing YES since the engine ran well when you switched the PMag out of the loop.
 
That's interesting

tin man said:
Don't understand why some people on this site question other peoples decisions when it comes to safety. Here's AWAG. Possibly a defunct mag has shed a part or two into the engine.
Tin Man
Click to expand...

That's interesting.

Bob Axsom
 
Ron Lee said:
Does the ignition curve change mean that the Pmag could/would have fired at a bad time and resulted in the symptoms that you saw? I am guessing YES since the engine ran well when you switched the PMag out of the loop.
Click to expand...

That's correct. The "curves" are a way of mapping ignition timing advance to piston position in relation to some fixed point. As far as I know, most use Top Dead Center as reference. If the curves (or maps) have shifted, then it's possible for the engine to behave oddly or just stop running entirely. In my case, this was seen as surging and high CHTs.
 
Rick S. said:
Heh heh....didn't you get that P-mag off E-bay Kevin for a "steal";) If I remember right. Didn't need my hangar this time...Glad you got her back and fixed.
Click to expand...

Ouch! Actually, I got it on these very classifieds for a steal. I'm back home next week. Give me a call sometime will ya?!
 
E-Mag / P-Mag

I am interested in the root cause of this problem. I spent a lot of time last year deciding on the ignition system for my new Aerosport IO-360. Up until the end, I was going to go E-Mag / P-Mag, but read through this and other forums of software problems - so I went with 1 Lightspeed and 1 regular mag.

The E-Mag / P-Mag concept is still intriguing, but how many times will we have to be told the software problems are solved?
 
The issues with Pmags may be birthing issues for a new system. The one thing that people using them should consider, and possibly any ignition system, is that if you have a sudden engine problem, part of your diagnostic process may be to switch from BOTH to Left and RIGHT. While this may not solve the source problem if it is related to one ignition system, it may allow the engine to run smoothly as you get to a suitable landing spot.
 
I received the P-Mag this morning, went to the airport and had it back in and timed in under an hour. I do love the installation of the E/P Mags. I did a few circuits around the pattern and departed for a quick run through the hills. Everything ran fine. I'll do some more local stuff before venturing back to Vegas but thanks to everyone for help and input.

On a side note, Aluminum Overcast was at Gillespie today. I can now say I've been in the pattern with a B-17. That is an impressive piece of machinery. I wish I could afford a ride in it!
 
You must log in or register to reply here.